Under the appropriate conditions, a patch of light appears considerably brighter when briefly flashed than when viewed for longer durations. This aspect of visual perception is known as temporal brightness enhancement, or the Broca-Sulzer phenomenon. Previous psychophysical experiments have demonstrated several stimulus variables which influence the magnitude of brightness enhancement and the related phenomenon of temporal contrast enhancement. The proposed project is designed to continue this investigation. One series of experiments will test the hypothesis that brightness enhancement is mediated by a population of neurons characterized as transient-type. Other experiments will assess the effects of overall light adaptation on brightness and contrast enhancement. In addition, brightness versus duration curves will be measured for luminance decrements. The results of these experiments are expected to provide a more complete picture of the physical correlates of brightness enhancement, as well as to provide information about its possible neural correlates.